Having a good ear is an important part of being a good musician. Apart from the obvious advantage of being able to hear whether you are playing the right notes or not, it enables you to becomes better at learning new pieces of music more quickly, memorising them, putting expression into them; and playing with other musicians. Having a good ear, along with knowledge and understanding of music theory and good technique is important for developing all round musicianship. Follow the links above to read about how you can develop your musical ear.